Keswick, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 49.2 °F (low) to 75.6 °F (high). Annual precipitation averages 51.9 Inches. Keswick is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Feb. 1 - Feb. 10 through the first frost around Dec. 11 - Dec. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 37.5 °F | 56.1 °F | 8.97 in. |
| February | 39.3 °F | 60.1 °F | 9.11 in. |
| March | 41.7 °F | 64.8 °F | 7.7 in. |
| April | 45.3 °F | 70.9 °F | 3.76 in. |
| May | 52.5 °F | 80.4 °F | 2.64 in. |
| June | 59.6 °F | 89.6 °F | 1.27 in. |
| July | 64.6 °F | 98.2 °F | 0.1 in. |
| August | 62.7 °F | 97.0 °F | 0.18 in. |
| September | 58.1 °F | 91.7 °F | 0.51 in. |
| October | 50.4 °F | 79.1 °F | 2.4 in. |
| November | 41.9 °F | 63.7 °F | 5.48 in. |
| December | 37.3 °F | 55.0 °F | 9.76 in. |
| Annual | 49.2 °F | 75.6 °F | 51.88 in. |
| Average First Frost Date | Dec. 11 - Dec. 20 |
| Average Last Frost Date | Feb. 1 - Feb. 10 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9b : 25°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 9b : 25°F to 20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |